Last Modified: Monday, March 21, 2011 at 11:38 a.m.

An oily substance washed up on Grand Isle, Elmer's Island and other nearby areas on Saturday. Tests on that substance are not complete.

It could be related to a well south of Grand Isle that leaked for four to six hours. Jefferson Parish officials said that leak is now plugged.

After completing an aerial survey of the spill with Jefferson Parish President John F. Young Jr. Sunday afternoon, Grand Isle Fire Chief Aubrey Chiasson said they saw patches of “light- to moderate-weathered oil” starting about three miles from the Caminada Pass in the Gulf and stretching out at least five miles.

Lafourche spokesman Brennan Matherne said the parish's Office of Emergency Preparedness was working with the Coast Guard to track the oil coming to Fourchon Beach.

“It's not the heavy brown and black oil, it's just the sheen that hit Fourchon Beach,” Matherne said.

ES&H is handling cleanup on the shorelines.

The Coast Guard also investigated a miles-long patch of discoloration off the Louisiana coast, which it now says was likely caused by Mississippi River sediment.

Testing on Sunday revealed the patch, an estimated 100 miles long and six miles wide, contained only trace amounts of petroleum that were well below the state of Louisiana's standard for clean water.

On Sunday afternoon, Jefferson Parish President John Young spoke to reporters about what officials referred to as ribbons of oil to the west of the main island of Grand Isle, near Elmer's Island and Caminada Bay.

“It looks similar to what we saw at the height of the oil spill,” Young said. “Browning, orangeish, oil (mixed) together with what appeared to be dispersant. We don't know.”

“In the meantime we're getting boom out there to try and cut off that cut that allows this substance, we think it's oil, to go into the marsh behind Elmer's Island,” Young said.

The Associated Press contributed to this report. Staff Writer Eric Heisig can be reached at 857-2202 or eric.heisig@houmatoday.com. Follow him on Twitter @TerrebonneCrime.

<p>GRAND ISLE — The Coast Guard is investigating two separate oily sheens spotted off Louisiana's coast. Neither is believed related to the BP oil spill, officials said.</p><p>An oily substance washed up on Grand Isle, Elmer's Island and other nearby areas on Saturday. Tests on that substance are not complete.</p><p>It could be related to a well south of Grand Isle that leaked for four to six hours. Jefferson Parish officials said that leak is now plugged. </p><p>After completing an aerial survey of the spill with Jefferson Parish President John F. Young Jr. Sunday afternoon, Grand Isle Fire Chief Aubrey Chiasson said they saw patches of “light- to moderate-weathered oil” starting about three miles from the Caminada Pass in the Gulf and stretching out at least five miles.</p><p>Lafourche spokesman Brennan Matherne said the parish's Office of Emergency Preparedness was working with the Coast Guard to track the oil coming to Fourchon Beach.</p><p>“It's not the heavy brown and black oil, it's just the sheen that hit Fourchon Beach,” Matherne said.</p><p>ES&H is handling cleanup on the shorelines.</p><p>The Coast Guard also investigated a miles-long patch of discoloration off the Louisiana coast, which it now says was likely caused by Mississippi River sediment. </p><p>Testing on Sunday revealed the patch, an estimated 100 miles long and six miles wide, contained only trace amounts of petroleum that were well below the state of Louisiana's standard for clean water. </p><p>On Sunday afternoon, Jefferson Parish President John Young spoke to reporters about what officials referred to as ribbons of oil to the west of the main island of Grand Isle, near Elmer's Island and Caminada Bay.</p><p>“It looks similar to what we saw at the height of the oil spill,” Young said. “Browning, orangeish, oil (mixed) together with what appeared to be dispersant. We don't know.”</p><p>“In the meantime we're getting boom out there to try and cut off that cut that allows this substance, we think it's oil, to go into the marsh behind Elmer's Island,” Young said.</p><p><i>The Associated Press contributed to this report. Staff Writer Eric Heisig can be reached at 857-2202 or eric.heisig@houmatoday.com. Follow him on Twitter @TerrebonneCrime.</i></p>